The present disclosure relates to subject matter contained in priority Japanese Patent Application No. 2001-65978, filed on Mar. 9, 2001, the contents of which is herein expressly incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a bonding method and apparatus for performing a bump bonding and a wire bonding.
2. Description of Related Art
A flip chip technique and a wire bonding technique are known as techniques for mounting semiconductor electronic components such as a bare chip type of semiconductor integrated circuit chips (IC chips) on a circuit assembly having substrates, parts and others.
Recently, IC chips have been progressively smaller and thinner with miniaturization of portable electronic devices. Apparatus for performing bump bonding to respective electrode pads on semiconductor wafers before dicing, have been provided.
As shown in FIG. 15, a bonding stage 110 of a conventional bump bonding apparatus positions a semiconductor wafer 201 and adherently holds the wafer through a plurality of suction holes 111, and heats the wafer having a circuit formed thereon to a temperature required for forming bumps on electrodes on the circuit using a heater 30.
A bonding head 120, which forms bumps on the electrodes on the semiconductor wafer 201, has a wire supply 121 for supplying gold wire 31 as a material for the bump, a ball press tool 122 for melting the gold wire 31 to be formed a molten ball and pressing the ball to the electrodes, and a ultrasonic wave generator (not shown) for providing ultrasonic wave effect on the bumps during the press. The bonding head 120 is positioned on an X-Y table 160 having a ball screw and movable along X and Y directions perpendicular to each other in a plane, and the table 160 drives to move the bonding head 120 so that the head forms bumps on predetermined electrodes on the semiconductor wafer 201.
In the above conventional bump bonding apparatus, however, following problems exist when a thin semiconductor wafer of which thickness is about 0.2 mm and lower is used.
First, when the semiconductor wafer is pinched by a transfer device of the bump bonding apparatus, crack or chipping tends to occur in the wafer due to mechanical stress.
Further, when the semiconductor wafer is adherently held through the suction holes 111 on the bonding stage 110, an area 200a in the wafer 201 located above the hole 111 (see FIG. 16) indents into depth of the hole 111, and circuits in the wafer may break or the entire area 200a may be damaged. In addition, in the area 200a, since the area 200a is suspended in air, the ultrasonic wave, used for bumping or wire bonding, is transmitted worse and bumps may be non-deposited, or crack and breach may occur in the wafer 201 when the ball press tool of the bonding head 120 presses the wafer 201 during the bonding.
In case of a thin wafer having a circuit-forming side covered by a protective polyimide film, the wafer often warps up toward the circuit-forming side in such a configuration that its border displaces upwardly about center of the wafer. Such a semiconductor wafer is hard-to be adhered to the upper face of the bonding stage 110 through the suction holes 111, and vicinity of the border frequently remains displaced. When the bumping is performed to the semiconductor wafer on the bonding stage 110 in this condition, if the bonding is required a load not more than a downward load for correcting the displacement near the border, in most cases the ultrasonic wave is applied to the molten ball in a condition that the border of the wafer is left floating in air, so the ultrasonic wave cannot be transmitted sufficiently to the molten ball, and thus the bumps may probably be non-deposited.
In light of the foregoing prior art problems, the present invention is directed to solve the above problems regarding the carrying of the semiconductor wafer and the hold of the wafer during the bonding. That is, an object of the invention is to provide a bonding method and apparatus where damage such as a crack, chipping, and break of the circuit do not occur in the wafer during the carrying, in addition the damage of the wafer and the break of the circuit during the suction and hold of the wafer, and the break of the wafer and the rising of the border of the wafer during the bumping are avoided.
To achieve the above objects, according to the invention, a carrier tool having a protective ring with a sheet extended over its underside is used, a semiconductor wafer is made to adhere to the sheet of the carrier tool, the wafer, being surrounded by the protective ring, is carried from a container device into a bonding stage, bonding is performed on the bonding stage, and the wafer is carried out of the bonding stage into another container device.
While novel features of the invention are set forth in the preceding, the invention, both as to organization and content, can be further understood and appreciated, along with other objects and features thereof, from the following detailed description and examples when taken in conjunction with the attached drawings.